Definition of fat

fat - adj. a chubby body; having much flesh (especially fat); marked by great fruitfulness; lucrative; having a relatively large diameter; containing or composed of fat; noun a soft greasy substance occurring in organic tissue and consisting of a mixture of lipids (mostly triglycerides); excess bodily weight; a kind of body tissue containing stored fat that serves as a source of energy; it also cushions and insulates vital organs; verb make fat or plump.